The present invention relates to a cassette for an ink ribbon which includes a cassette casing and drive elements.
Cassettes of the type to which the invention pertains may include driven, journaled rollers (pulleys etc.) and friction means arranged between the ribbon and the roll or pulley whereby the roll or pulley is connected with a coupling element penetrating the cassette casing. Moreover such a cassette includes on the exit side a brake element and the casing is covered by a releasable cover.
Such ink ribbon cassettes particularly for colored ribbons and multicolor dyes are usable as exchange modules to be inserted for example in typewriters, printers including for example matrix printers and other office machines. Whenever a ribbon is to be exchanged the cassette as a whole is removed and replaced by a new one. This of course facilitates greatly the exchange of a spent ribbon for a fresh one, however this procedure entails a relatively expensive practice particularly if the cassette is subsequently just discarded.
Generally speaking it is also well known to consider one and the same cassette as being a more or less integral or associated element with the office machine to which it pertains and with which such a cassette cooperates. Under such aspect one may have for example another cassette just for the ribbon. When the ribbon is spent this exchange cassette is replaced by a fresh one in the basic cassette which remains in place. In other words there is a regular or basic cassette which includes traction means and a particular type of ribbon exchange cassette which is removably and replaceably inserted in the basic cassette to permit ready and easy exchange of the ribbon as so understood. This arrangement however has the drawback of a considerably larger space requirement for the ribbon exchange cassette within the basic cassette. Since the space to be occupied by any inserted cassette in the office machine is limited and since particularly length dimensions cannot be changed, it turns out that in the conventional device the ribbon exchange cassette for such a basic cassette occupies as such space in the latter which can come only from ribbon material so that the length of the ribbon to be accommodated is reduced. This means that the exchange has to take place in more frequent intervals. High performance printers i.e. high speed printers printing for example 400 characters per second consume in that sense ribbon material rather rapidly which in turn means that the exchange of ribbon slows down in effect the printer operation.